In general, conventional conductive devices for application to the skin, include those comprising two metal plates insulated from each other by an insulant disposed between them, wherein one metal plate is made from a metal having higher ionization tendency, while the other metal plate is made from a distinct metal having a lower ionization tendency.
Such a conventional conductive device is disclosed in Japanese Utility Model Application No. 57-197841 (laid open for inspection Jul. 10, 1984 and published Mar. 8, 1985). This conductive device comprises a small disk-like copper plate having a lower ionization tendency, and an aluminum ring-plate having a higher ionization tendency, which is engaged to the copper plate with a space disposed therebetween. The copper plate is disposed onto a central portion of an adhesive sheet coated with insulative adhesives. This device is further characterized in that the copper plate and the aluminum plate are provided on the adhesive surface of the adhesive sheet to avoid direct contact each other by forming a space between the two plates for insulation. When alleviation of such symptoms as musculoskeletal discomfort or pain is desired, the device is applied to a position on the skin immediately above the area of discomfort by attaching the adhesive sheet onto the skin so that the copper plate is contacted with the central area of the skin directly above the area of discomfort, while the aluminum plate is contacted with the area surrounding the central area. Thus, negatively charged particles flow into the region of discomfort in a direction from the copper plate to the aluminum plate due to the difference of the ionization tendency therebetween. The stream of charged particles produced may result in the correction of any deviation of biogalvanic electricity in the body of the subject and may exert effects to alleviate shoulder discomfort and the like via the relaxation of muscle(s), tendon(s) and the like.
In addition to the conductive device discussed above, similar effects may be expected by employing an iron plate thinly-coated with copper and an iron plate thinly-coated with aluminum-zinc, as alternatives to the combination of the copper and aluminum plates.
Although the aforementioned conductive device has been known to exert excellent effects, the thickness and total weight thereof tend to be prohibitive due to the metal plates employed. Additionally, since the space disposed between the copper plate and the aluminum plate must be maintained for insulation purposes, thickness of the aluminum plate must be larger in accordance with the width of the space. Thus, the subject may be prone to unpleasant sensations caused by such thickness and weight.
Furthermore, the elasticity of the conductive device is poor due to the metal plates employed. More specifically, when the device is applied to a non-flat or a curved portion of the body (e.g., "therapeutic point" on the fingers, or joints of the arm and the like), it is difficult to adhere the device to cover such an uneven surface. In addition, when the device is applied to such uneven surface, the user may be subject to an unpleasant sensation of a resistive force resulting from failure of the device to deform in correspondence to the movement of the "therapeutic point" or joint.
With respect to economic considerations, the per unit cost of a conventional conductive device is necessarily inflated due to the special manufacturing techniques needed with respect to the different metal plates employed therein. More specifically, when iron plates thinly-coated with copper or aluminum-zinc are employed, foundational coating with a metal such as nickel or the like is necessary for the prevention of rust prior to the thin-coat application. As a result of this necessity, the manufacture of such a conventional device is somewhat complicated and therefore costly.